Fluid pressure biased squeegee blade and counter pressure table therefor

ABSTRACT

Printing apparatus for printing machines of the type having cylindrical screens and an endless carrying belt is disclosed which comprises a squeegeeing device consisting of an elastic membrane expansible by means of a pressurized fluid (such as air), said membrane being associated with an equalizing bar placed between the said membrane and a blade made of a flexible and elastic material acting on the internal surface of the screen with an acute incidence angle, said squeegeeing device being opposed to a counterpressure table inclined with respect to said endless carrying belt, said counterpressure table being provided with a lining consisting of layers of soft and yielding material and of an anti-frictional thin plate. The zone of contact between said endless carrying belt and said counterpressure table is placed downstream of the contact zone between the endless carrying belt and said screen. The said counterpressure table forms with the horizontal plane tangent to said screen an angle between 3* and 6*.

Giani FLUID PRESSURE BIASlED s EEEcEE BLADE AND couNTEn PRESSURE TAEEE THEREFOR Inventor: Adolfo Giani, Bergamo, Italy [73] Assignee: Reggiani S.lP.A., Bergano, Italy [22] Filed: Mar. 7, 1972 [21] Appl. No.: 232,593

[30] Foreign Application Priority Data Mar. 12, 1971 Italy 21677 A/71 [52] -U.S. Cl 101/119, 101/120, 101/126, 101/407 R [51] Int. Cl. B411 15/08, B41f 15/24 [58] Field of Search... 101/116,119,120,126,123, 101/124, 407 R, 407 B1, 407 A; 118/205, 21 1, 213

[56] References Cited UNITED STATES PATENTS 1,566,358 12/1925 White. 15/2565 3,029,779 4/1962 l-lornbostel 118/104 1 3,735,730 5/1973 'Mitter 101/119 X 3,110,919 ll/1963 Barnby 101/120 UX 3,116,688 1/1964 Ward, Jr. et al..... 101/350 2,698,574 ll-l955 Dougherty et a1... 101/120 2,424,949 7/1947 White 101/120 UX 2,423,391 7/1947 Kozloff..... 101/126 X 3,587,458 6/1971 Feier et a1. 101/120 X 2,292,602 8/1942 Biondi 1.01/1'16 Mar. 5, 1974.

FOREIGN PATENTS OR APPLICATIONS 2,006,887 l/1970 France 101/120 Primary Examiner-Emest T. Wright, Jr. Assistant ExaminerR. E. Suter Attorney, Agent, or Firm--Stevens, Davis, Miller &

' Mosher [5 7] ABSTRAQT Printing apparatus for printing machines of the type having cylindrical screens and an endless carrying belt is disclosed which comprises a squeegeeing device consisting of an elastic membrane expansible by means of a pressurized fluid (such as air), said membrane being associated with an equalizing bar placed between the said membrane and a blade made of a flexible and elastic material acting on the internal surface of the screen with an acute incidence angle, said squeegeeing device being opposed to a counterpressure table inclined with respect to said endless carrying belt, said counterpressure table being provided with a lining consisting of layers of soft and yielding material and of an anti-frictional thin plate.- The zone of contact'between said endless carrying belt and said counterpressure table is placed downstream of the contact zone between the endless carrying belt and said screen. The said counterpressure table forms with the horizontal plane tangent to said screen an angle between 3 and 6.

6 Claims, 1 Drawing Figure FLUID PRESSURE ETASED s UEEcEE BLADE AND COUNTER PRESSURE TABLE THEREFOR The present invention relates to a printing apparatus for use on cylindrical screen printing machines for fabrics and ribbon-like materials in general.

More particularly, the invention relates to a device for distributing the dye and to a so-called counterpressure table.

lt is'well knwon that one of the most commonly used types of machines for the printing of fabrics in particular, and of ribbon-like materials in general, comprises substantially an endless carrying belt which carries the ribbon to be printed; cylindrical rotary screens revolving in concert with the endless carrying belt; devices for the feeding of the dyes to the surface of the cylindrical screens; devices for the distribution of the dye (commonly called squeegees); and counterpressure surfaces arranged underneath the endless carrying belt and opposed to the screens.

These known machines are very fast operating but not as precise as desired, wherefore they are not suited for the production of printed fabrics of high quality.

The greatest limitations on the use of these machines are due to the poor efficiency and excessive wearability of the squeegees and screens as well as to an uneveness of the pressures and, thus, of the wear, at the mutual contact points of the various moving parts.

Thus, the printing quality that is already poor even under the best operating conditions will gradually deteriorate as time elapses. Therefore, frequent overhauls or replacements of parts of the machine become necessary One object of this invention is that of providing -a printing apparatus for cylindrical screen printing machines that will ensure uniform pressures between the various moving parts, that is composed of durable or relatively non-wearable devices or of devices only subject to local wear in parts easily and cheaply'replaceable, and that shall enable one to obtain high quality printing.

Other objects and advantages of this invention will become apparent from the following description of a printing apparatus for printing machines with cylindrical screens and an endless carrying belt, which apparatus comprises, according to the invention, a squeegeeing device consisting of an elastic membrane, expansible by means of a pressurized fluid, the membrane being associated with an equalizing bar arranged between the same membrane and a blade of flexible and elastic material acting on the internal surface of the cylindrical screen with an acute incidence angle, and there being opposed to said squeegeeing device a counterpressure table inclined, with respect to said endless carrying belt, preferably at an angle between 3 and 6,

-said counterpressure table being provided with an at 7 least double lining formed of layers of soft and yielding material, preferably felt and/or foam-rubber, and with an anti-frictional thin plate having one of its ends constrained with respect to the counterpressure table and the opposite end free and in contact with the endless carrying belt, said contact occurring downstream of the point of contact between the endless carrying belt and the screen,

The invention'will now be described in still further detail by reference to the attached drawing wherein there is reproduced in cross-section an embodiment of a purely exemplifying and non-limiting character.

In the drawing, 1 indicates part of a perforated cylindrical screen of an otherwise conventional machine for printing fabrics or ribbon-like materials in general.

The material to be printed is attached to and carried by the endless carrying belt 2 and is thus mobile with the same. As shown by the arrow A, the endless carrying belt 2 moves in a direction toward the left in the drawing.

Inside the rotary screen 1 there is arranged a dye collector or reservoir 3 which forms one single body with the squeegee-holder 4. The squeegee consists of a membrane or hollow body 5 parallel to the axis of the screen 1, a cylindrical bar 6, and blade 7.

Membrane 5 is fed with a pressurized fluid through pipe 8 and pressure regulator 9. Upon increase of the pressure of the fluid, the membrane 5 swells out pushing downwardly the bar 6 which, together with the membrane, is arranged in a channel-like seat opening downwardly, and formed by the lower end of the squeegee-holder 4.

Bar 6 acts on blade 7 with a force which is proportional to the pressure of the fluid contained within the membrane 5.

The blade 7 is made of bronze or steel, or any other suitable flexible and elastic material in general. It is attached to the squeegee-holder 4, by a curved plate 10 and screws Ill. The other end of blade 7 is in contact with the internal surface of the screen 1 at an incidence angle which is acute.

The quantity of dye 12 (coming from the collector or reservoir 3 in a way not shown in the drawing -for the sake of simplicity) that, passing through screen 1, is deposited on the ribbon to be printed, depends on the angle of incidence between the blade 7 and a counterpressure-table l3.

It is quite clear from what has been said above, that said angle of incidence may be adjusted at will by varying the pressure of the fluid contained within the membrane 5. The angle of incidence is constant throughout the various cross-sectional planes of the screen 1, thus insuring a uniform printing.

The counterpressure table 13 consists of a flat surface, inclined with respect to the endless carrying belt 2, curving over lateral supports 14 and 15 fixed in turn to beam 16.

The counterpressure table 13 is covered by a double layer of felt, fixed to the lateral supports 14 and15 by means of angle irons l8 and 19.

An anti-friction plate 20 conventionally made of bronze, bronze alloys or stainless steel forms the surface of the counterpressure table 113 which supports the moving belt 2. As shown in the drawing, one end of the plate 20 is fixed between the felt layer 17 and the angle iron 19. The middle portion of the plate 20 rests on the felt layer 17 and the other, free, end of the plate (opposite the fixed end) overhangs the counterpressure table 13 adjacent thelateral support 14!, in cantilever fashion. The plate 20 is made of a friction-reducing material to allow the belt 2 to slide freely over the overhanging portion of the plate on which the belt is supported.

As will be observed from the attached figure, the contact zone between the anti-friction thin plate 20 and the endless carrying belt 2 is staggered with respect to the zone of contact between the screen 1 and the same endless carrying belt 2. More particularly, the former 3 is downstream of the latter (with respect to the direction of advancement of the endless carrying belt 2).

As a matter of fact, it has been found that in this way the penetration of the dye into the material to be printed may be readily varied at will by adjusting the pressure of the fluid contained within the membrane 5.

The penetration of the dye depends on the contact time between the screen 1 and the material to be printed.

, Increasing the pressure of the fluid contained within the membrane increases the arc of contact between the screen 1 and the carrying belt 2 and, consequently, both the contact time as well as the penetration of the dye increase.

Moreover, it has been found that the best conditions for achieving good printing effects; and for avoiding excessive strains on the screen, on the squeegee and on the other parts in mutual movement with respect to each other, are achieved when the angle which the counterpressure table 13 forms with the endless carrying belt 2 (or, more exactly, with the horizontal plane tangent to the screen 1) is between 3 and 6.

The lining of the counterpressure table 13 may be completed if desired by a layer of foam-rubber placed underneath the felt layer 17. This lining and the thin plate insure in any case a smooth and jerkless sliding, with little friction and wear, of the endless carrying belt 2, with consequent precise printing of the fabric or ribbon-like materials carried thereon.

Similarly convenient operational conditions are obtained with the squeegee device by the fact that the blade 7 is subjected to the greatest part of the wear, which blade is easily and cheaply replaceable.

What'is claimed is:

1. Apparatus for use with cylindrical screen printing machines, comprising:

a movable belt for carrying a ribbon of material to be printed;

a rotatable cylindrical screen mounted for rotation in contact with said ribbon on said movable belt;

a squeegee holder member mounted inside said screen and having a channel-like seat opening downwardly from one portion of'said holder and extending parallel to the rotational axis of said screen;

an expandible elastic membrane mounted in said channel-like seat;

fluid pressure means coupled to said membrane to pressurize and expand said membrane in a controllable manner;

a blade of flexible material mounted for contact with the interior surface of said screen and formingan acute angle of incidence with said movable belt;

a cylindrical member mounted in said channel-like seat in contact with said elastic membrane and said blade, said membrane acting on said blade through said cylindrical member such that expansion and contraction of said membrane causes a change in the incident angle of said blade; and

a counterpressure table disposed adjacent the opposite surface of said belt from said screen, said table having a surface portion in the region opposite said screen inclined with respect to said belt and including a lining of yieldable material covering at least a portion of the surface of said table, and a plate having one end portion fixedly mounted to said table and an opposite end portion overhanging said table and spaced therefrom, said movable belt being supported at least by said overhanging end portion of saidplate.

2. Printing apparatus according to claim 1, wherein said movable belt contacts said counterpressure table at a region downstream of a region of contact between said belt and said screen.

3. Printing apparatus according to claim 1, wherein said lining of yieldable material covers at least said inclined surface portion of said table and said plate has a middle portion which rests on said yieldable material covering said inclined surface portion of said table.

4. Printing apparatus according to claim 3, wherein said inclined surface portion of said counterpressure table forms with the horizontal'plane' tangent to said cypressure table itself.

lindrical screen an angle between approximately 3 and 

1. Apparatus for use with cylindrical screen printing machines, comprising: a movable belt for carrying a ribbon of material to be printed; a rotatable cylindrical screen mounted for rotation in contact with said ribbon on said movable belt; a squeegee holder member mounted inside said screen and having a channel-like seat opening downwardly from one portion of said holder and extending parallel to the rotational axis of said screen; an expandible elastic membrane mounted in said channel-like seat; fluid pressure means coupled to said membrane to pressurize and expand said membrane in a controllable manner; a blade of flexible material mounted for contact with the interior surface of said screen and forming an acute angle of incidence with said movable belt; a cylindrical member mounted in said channel-like seat in contact with said elastic membrane and said blade, said membrane acting on said blade through said cylindrical member such that expansion and contraction of said membrane causes a change in the incident angle of said blade; and a counterpressure table disposed adjacent the opposite surface of said belt from said screen, said table having a surface portion in the region opposite said screen inclined with respect to said belt and including a lining of yieldable material covering at least a portion of the surface of said table, and a plate having one end portion fixedly mounted to said table and an opposite end portion overhanging said table and spaced therefrom, said movable belt being supported at least by said overhanging end portion of said plate.
 2. Printing apparatus according to claim 1, wherein said movable belt contacts said counterpressure table at a Region downstream of a region of contact between said belt and said screen.
 3. Printing apparatus according to claim 1, wherein said lining of yieldable material covers at least said inclined surface portion of said table and said plate has a middle portion which rests on said yieldable material covering said inclined surface portion of said table.
 4. Printing apparatus according to claim 3, wherein said inclined surface portion of said counterpressure table forms with the horizontal plane tangent to said cylindrical screen an angle between approximately 3* and 6*.
 5. Printing apparatus according to claim 1, wherein said flexible blade is attached at one portion to a side of said squeegee holder displaced from said seat in the longitudinal direction of travel of said belt, said blade having a second portion which extends transversely to a plane substantially normal to the longitudinal direction of travel of said belt and passing through said elastic membrane.
 6. Printing apparatus according to claim 1, wherein said lining of the counterpressure table comprises layers of felt fixed onto lateral supports of the counterpressure table itself. 